Magnetically Induced Circular Dichroism and Birefringence in Single Lines of the Electronic Spectrum of ICl

Abstract

The magnetically induced circular birefringence and dichroism of several bands in the electronic spectrum of ICl have been studed with a resolution of approximately 0.1 cm−1. The frequency dependence is in agreement with predictions based on the semiclassical dispersion formulas provided that each Zeeman component of a single zero-field line is treated separately. The line center is displaced by the Zeeman shift and the intensity is determined by first-order perturbation by the magnetic dipole-moment operator which mixes neighboring J states. Thus, although the qualitative aspects of the semiclassical treatment of the Faraday effect may be extended into regions of the spectrum in the immediate vicinity of sharp-line molecular spectra, the details of the spectrum depend in a very sensitive way on the molecular parameters and the rotational structure of the band.